Safety-fuse.



1 9 1 6 w M m m a D..

FGL

INvENTon sfrATEs rATENT ALBERT F. BAUM, OF PITTSBURGH, 1 ?ENNSYIVAIVTIA.

sAFETr-Fnsn.

Appiianon rue .my 7, 1911, serial No. 637,322:

To all whom t may concern Be it known that ALBERT F. DAUM, a citizen of the United States, residing at Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented new and usefil Improvements in. Safety-Fuses, of which the following is a specification.

My invention relates to'safety fuses, and has particular reference to that type of fuses called cartridge-fuses, or fuse-shells; but I do not limit my invention to this type of fuses except so far as the claims admi-t of no other reasonable construction.

The more important objects of my invention are to construct a cartridge-fuse or fuse-shell so that it will indicate whether or not it has blown; .to do away with the threading of at least one end of the body and of at least one of the caps; to increase the area of contact of the fuse-shells with the 'conduictor terminals which the fuseshells connect in circuit; to provide molding or elastic supports for one or both vends of the fuse-shells so that supports for the ends of the fuseovires may, on the blowing of the4 fuse-wires, become more widely Iseparated; thereby preventing the restablishment of the circuit through the fuse-wires; to clamp the ends of the fuse-shells tightly to the terminals and at the same time increase the contacting surface of the fuse-wires with the terminals of the fuse-shells and to bind the ends of the fuse-wires tightly to the fuseshell terminals; and to cheapen and simplify the class of articles to which my invention belongs. l f

Referring to the. accompanying drawing, Figure l' is a central longitudinal section through a safety-fuse and its connections constructed in accordance with one form of my invention; Fig. 2, an end view thereof; Fig. 3, a cross-section on the line III-III,

vFi l' F'iff. ll. a cross-section on .the line IV--IV, Fig. l; Fig. 5, aportion of one end .of a. second form of my invention, together with the support therefor,- parts being in section; Fig. 6, a plan of Fig; 5, the brokenaway part being restored; Fig. 7, a view similar in character to Fig. 5, butshowing a third form of my invention; Fig. 8, a side view of one end ozt' a safety-fuse and its support, showing a fourth form of my invention; Fig. 9, ongtudinai section of ,one`

Specication of Letters Patent.

Patented May ti, Renewed December 2,'1912. Serial No. 734,626.

4end of a safety-fuse and its support showa ing a fifth form of my invention; Fig. it?, an end view of Fig. 9; and Fig. l1, a section olf one end of a safety-fuse, partly in elevation, showing a sixth -fcrm 'of my invention.

Referring first to Figs. l to 4, l represents the preferably cylindrical easing of insulat` ing material, such, for example, as glass, porcelain, fiber, or vnlcanite. f The ends of the casing l are provided with preferably copper caps 2, one or both of which may have a loosely fitting sliding ortelescopic relation to the casing lsas shown on Fig. l'. or threadedl relation therewith, as shown on F ig. ll, where the cap is marked 2a and the casi-ng la. m

Referring now to the left-hand end of Fig. l and to Fig. 3, 3 designates a headbe" tween the end of the casing l and the end of the cap 2. The headw 3 has at least Vone transverse opening, asjt, to receive one end of at least one fuse-wire, as 5, which has the end beyond the'head 3 bent so as to lie against Ithe outer face of the head. --The head 3 has ,of the cap, the hole opening into the interior of the casing. The nut 7 works on `the sev stem 6. 8 represents an insulating base, onT

which any number of pairs of terminals 9 may be secured, as by the bolts 10. The terminals have the ends extending at a right angle to each other and slotted to receive the stems 6 and the bolts 10. vThe members of each pair of terminals 9 are spaced apart so that their inner or opposing faces can rest against the ends of the caps when the nnte Z are screwed up tightly against the enter faces of the te, rminals. By turning up the nuts tightly, the ends of the fuse wire 5 are tightly clamped between the caps and the adjacent heads so as to make broad and close electric connections. The head 3, the stem 6 and the nut v7 are all preferably good conductors of electricity' but they or any of them might in some instances be made of P001' or non-conducting'material. I have Yshown the nuts in Figs. 1, 2, and 8 designed for operation by a wrench, while in Fig. 11,

I have 'shown the winged nut designed forhand operation.

Referring now to the righthand' end of Fig; 1 and to Fig. 4, the partsy are the same end caps (depending on presence or as at the left'hand of 1, except that the head ais .made oblong with its extremities seated in. recesses-vin the end of the casing .toprevent any liability of theA stem 6 turning when the nut 7 is actuated. The end of the fuse-wire passes between the side of the head 3a and the wall of the casing.

'When an'excessive current passesthrough the fuse-wire 5,'morev or less of it is melted andl converted `into metallic vapor with eX- plosive'violence causing one or both` of the absence of' one threaded cap, as shown in Fig. l1)

, to be driven a short distance outwardly as indicated by the dotted position of the ter- -minals 9 in'Fig. 1, whereby the fuse-wire is with certainty disconnected and prevented from reconnecting. It is with many cartridge 4fuses impossible to tell which of a numberA of them has been blown; but with my loosely fitting caps, the fact that a fuse has been blown canat once be told by the position of the cap or caps, which will be somewhat displaced from their normal position. When the casing is made of transparent glass, the blown fuse-wire can be at once directly detected also.

In Figs. 5 and 6, I have shown'the stem 6 unthreaded but with a longitudinal .slot 11 to receive the wedge 12, which takes the place of the nut 7 (Fig. 1) andtightlyclamps the terminal 9 between itself and the end of the cap 2.

In Fig. 7, the upstanding member of the terminal QVismade wedge-shaped as shown at 12EL and is resiliently Vor flexibly connected to the member in contact with the base 8. While Vthe upstanding member may be variously made, I have shown it, not of awvedgeshaped piece of Sheetmetal, but of a strip of metal bent to the shape 'of a wedge or triangle with theapeX rat itsouter end. The end of the cartridge-fuse, which is like that of Figs. 5 and 6, is forced down on the means, as j stem 6,

wedge 12a, the slot 11 receiving the wedge` it there,`so that it can be known from itsy displacement Aand that of the cap 2, that its fuse-Wire has been disconnected. The

.screw 13 serves asa means for adjustingv the tension of the sp1 ng 14.A It is readily understood that the terminal might itself be made of resilient material so put under strain that, when connected to the fuse- 'it is to pulls, the terminal to the.

Loenaee shells and released by the separation of the fusewvire, it will assume the dotted 'position shown in Figs. 1 and 8.

In Figs. 9. and 10, I have shopvn my in vention adapted for .use as a knife switch, or a cartridge-fuse with knife terminals. Instead of using the nut 7, I make the nut,l marked 7 b, of, oblong rectangular shape, like the ends of the well-known cartridgefuses with knife terminals integral with the end-caps. I provide oneend of the nut or knife-terminal 7" with the threaded hole l5 to fit the stem 6. The terminal or nut 7b is turned up tight against the end of the cap so as to clamp the end of the fuse-wire 5 between the cap 2 and the head 3. -The terminal 7l slides between theblades 16 of the base terminal 9b of usual \construction, the blades acting as vyielding or resilient holding means for the cap 2. When the fuse-wire 5'blows, the cap 2 will slide into engagement with the terminal 9b, thus indicating that -the cartridge needs a new fuse-wire. v

While I have shown only one end of several forms or designs 4of my invention, and in Fig. l I have shown'two forms thereof, be understood that the opposite ends of the cartridge fuses maybe alike or different, or one end only may contain. my present invention.. I have not shown the casing provided with a non-conducting filler as I have found it tobeunnecessary in most cases.

The cartridge-fuses alone do not comprise the line terminals 9,9, or 9", and where these terminals'are not desired, the fuses are shipped with the nuts 7 or 7a or the wedges 12 in engagement with the ends of the caps. The fuses fmay be used as shown in the drawings o r they may be left with the nuts or wedges in contact with the caps, each of which may be inserted between spring terminals of the usual type. In some instances the nuts 7 or 7g or the'wedges'may be omitted, when the said usual spring terminalil for gripping the sides of the caps are use As will be seen, the memberr 3 or 3 is free from peripheral engagement with the end cap, and is also 'free'from any engagement wi h the shell 1 so faras'endwise movement of the shell' is concerned, the position of the member. y3""within the slots of the ,shell simply actingfto' prevent the member'fr'om' rotating relative to the shell,

but permitting the member to be drawn toward the end cap so asto' partially lift the member from the bottom of the recesses. It will therefore be understood`- that I have provided a construction .by `means of which the clamping action on the fuse element is provided solely .by the end cap and member, and that when this clampingaction is completed, the relative positions of the acera-2e I member and end cap are fixed, thereby eliminating any liability of the fuse element changing its contact relationship with.

either part while the fuse is in service, a positive advantage where there is shrinkage of the shell, or where there'is an arrangement of parts such, for instance as shown in Fig. 1 in which the end cap is free from positive connection with the shell. In the form shown in Fig. 1l, the shrinkage of the fiber when it becomes dry tends to loosen the threaded connection so as to permit a sli ht play between the opposing threads, an where, as -in the construction shown in my Reissue Patent #13,312, the end of the shell forms an abutment against which the member is held to provide t-he clamping action on the fuse element, this play may become serious in that it tends to destroy the contact between the fuse element and the 'member or cap. This objection is eliminated in the present invention by rea'- son of the fact that the end cap and mem ber are held in .fixed relationship so that relative movement of the shell and end cap has no eii'ect upon the clamping action or thecontact.

I claim- 1. In an electric safety apparatus, a casing of non-conducting material, an end cap therefor provided with a hole opening'into the interior of the casing, a clamping-head,

' a stem therefor 'extending through the hole l in the cap, a fuse-wire having one end lying between the head and the cap, .a terminal external to the cap, and means for causing the head to clamp the end of the fuse-wire Vbetween the head and cap arid `to'clamp -the terminal to the cap. v

2. In an electric safety apparatus, a casing of non-conducting material, an end cap thereforV provided with a hole opening into the interior of the casing,- a clamping-head, a stem therefor extending through the hole in the cap, a fuse-wire having one end lying. between 4the head and the cap, an electric terminal, and means coperating with the stem and acting on the terminal for simultaneously clamping the terminal to the .cartridge-fuse, 4and the fuse-wire between the head and the cap.

3. In an electrical apparatus, a casing, an end cap thereon, a bolt having its head within the casing and its stem extending through the end of the cap, a fuse within the casing and with one end between the bolt head and the cap, and a device movable with respect to the stem and coperating with the stem and the out-er face of the cap to clamp the fuse between the bolt head and the cap.

' 4. In a reillable fuse, an end cap, a shell adapted to extend into said'cap, a metallic member Within the end cap and Vfree 'from 4peripheral engagement with the skirt of the cap and coperating with the cap to secure a fuse element therebetween, said `member being also free from holding engagement with the shell, and means for positioning said member within said cap to provide a' normally fixed relation between said cap and member independently of the shell.

5. In a refillable fuse, an end cap, a shell adapted to extend into said 'capa metallic member within the end cap and free from peripheral engagement with the skirt of the cap 'and cooperating with the cap to secure a fuse element therebetween, and means for lpositioningsaid memberwithin the cap to provide a normally fixed relation between said cap andmember independently of the shell, a spring contact, said means including a stem carried by said member and extending through said cap, and external means for clamping said spring contact to the face of said cap, said latter Contact acting to exert an outward pull on the connecting members when the fuse blows.

Signed at Pittsburgh, Pa., 'this 6th day of July, A. D. 1911.

ALBERT F. iDAUM.V

Witnesses:

F. N. BARBER, ALICE E. DUFF. 

